perf srccode: Move struct definition from map.h to srccode.h

To reduce the header dependencies, since we already have a srccode.h
header, then there is where the 'struct srccode_state' should be, and
map.h, that is more widely used should have just a forward declaraion
of 'struct srccode_state'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-64lrkjjaa7wlo1zi2gr5u3es@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>